In order to remove the harmful substances such as CO, HC or NOx, etc. included in exhaust gas from vehicles, installing a catalytic converter in the exhaust system from engine to muffler has been widely adopted. As a catalytic converter, the three-element catalyst converter that uses Platinum (Pt), Palladium (Pd), Rhodium (Rh), Zeolite, etc. is used mostly common. This three-element catalyst converter is formed in honeycomb-like structure made of these materials. While the converter is used, exhaust gas with a temperature of 800_ is passed through the opening part of the honeycomb structure, so that oxidation and reduction with the harmful substances within the exhaust gas may take place. Poisonous CO and HC are oxidized to generate harmless CO2 and H2O, respectively. Furthermore, poisonous NOx is deoxidized to generate harmless N2 and O2. This is the principle of the three-element catalyst converter's operation. This three-element catalyst converter may take a shape of planular, elliptic cylinder, with a longitudinal size of 20-50 cm and a thickness of 10-20 cm. Weight of the unit including accessories is 10-20 kg.
On the other hand, in case of Diesel engines, mixed gas self-ignites by compression in the combustion chamber, and then the exhaust gas is evacuated through the exhaust pipe. Due to this operation principle, it is impossible to have the mixed gas completely combusted. Therefore, in case of Diesel engine, it is difficult to suppress the black smoke that is generated accompanying with imperfect combustion. The black smoke causes not only generation of air pollution, but also generation of a highly toxic dioxin or a carcinogenic substance by reacting with Cl, etc. At present, Diesel Particular Filter (DPF) consisting of an afterburner and a replaceable filter has been installed at the exhaust side in order to remove the black smoke generated from Diesel engine.
Exhaust gas regulations being strengthened, it has become necessary to install two or three catalyst converters in the exhaust system of the gasoline engine vehicles. FIG. 1 shows three catalyst converters equipped to a vehicle. The three-element catalyst converter 1 are provided in series between the exhaust manifold 2 and the muffler 4 in the exhaust system starting from the engine 5 and reaching the muffler 4. As described above, since the three-element catalyst converter has a substantial volume, there is a problem of difficulty to reserve a room to place two or three catalyst converters. In addition, since the catalyst converter has a significant thickness of 10 cm, when this is installed on the vehicle's floor, the vehicle's floor must be raised up, which results in a problem that decreases the inner space of the vehicle.
Furthermore, since the weight of the catalyst converter is 10-20 kg per unit, installing three catalyst converters means that the total weight of the vehicle increases by some tens of kilograms. Also, since the DPF is as heavy as 100 kg per unit, a problem of weight increase in case of Diesel engine is more serious than the case of gasoline engine. Such an increase of weight generates another problem of too much consumption of fuel. In addition, since the DPF is very expensive, it causes a problem of cost when DPF is equipped to vehicles.
Accordingly, the purpose of the invention is to provide a compact, light and low-cost liquid fuel reformer enabling to remove harmful substances from exhaust gas of vehicles.